This chapter examines the multifaceted transitions within China’s agricultural production systems and their corresponding environmental impacts. It highlights the demographic restructuring of rural areas, characterized by aging populations and labor migration, and investigates its cascading effects on farmland use, cropping structures, and mechanization. The shift toward non-agricultural employment has altered input strategies, intensified fertilizer application, and exacerbated non-point source pollution. Simultaneously, the evolution of farmland utilization, spanning from dominant to recessive transitions, reveals spatial and functional transformations driven by urbanization and market integration. The chapter critically engages with the environmental externalities of agricultural modernization, emphasizing non-linear dynamics and region-specific pathways of pollution and eco-efficiency. By identifying key research gaps in the systemic interactions between labor, land, and production, this study calls for a holistic framework to assess and govern agricultural sustainability in rapidly transforming rural contexts.